Fuel injection valve

ABSTRACT

A FUEL INJECTION VALVE FOR INTERNAL COMBUSTION ENGINE HAS A HOUSING HAVING A FUEL INLET AND A FUEL OUTLET. THE HOUSING HAS A VALVE SEAT HAVING AN AXIS AT THE FUEL OUTLET A VALVE MEMBER IS ARRANGED WITHIN THE HOUSING AND AXIALLY ALIGNED WITH THE VALVE SEAT AND MOVABLE ALONG THE AXIS THE VALVE SEAT BETWEEN A FIRST POSITION SPACED FROM THE VALVE SEAT AND A SECOND POSITION ENGAGING THE VALVE SEAT. AN ELECTROMAGNET IS PROVIDED WITHIN THE HOUSING WHICH INCLUDES AN ARMATURE CONNECTED TO THE VALVE MEMBER AND TOGETHER FORMING A UNIT FOR MOVING THE VALVE MEMBER AND SAID ELECTROMAGNET IS ENERGIZED FROM THE SECOND POSITION TO THE FIRST POSITION. A SPRING, ANCHORED AT ONE END OF THE HOUSING, COOPERATES WITH THE UNIT AND CONNECTED THERETO TO YIELDABLY MAINTAIN THE VALVE MEMBER IN THE SECOND POSITION. TWO MEMBRANES ARE PROVIDED WITHIN THE HOUSING WHICH ARE SPACED FROM ONE ANOTHER IN AXIAL DIRECTION OF THE VALVE MEANS. THE MEMBRANE BEING CONNECTED TO THE PARALLEL PLANES, EACH MEMBRANE BEING CONNECTED TO THE UNIT AND TO THE HOUSING FOR MAINTAINING A VALVE MEMBER IN AXIAL ALIGNMENT WITH THE VALVE SEAT. THE ELECTROMAGNET HAS A CENTRAL CORE COAXIAL WITH THE VALVE SEAT AXIS AND A COAXIAL ANNULAR POLE RING. THE ARMATURE HAS A PORTION WHICH MADE FROM SOFT IRON AND WHICH FACES THE CORE AND THE POLE RING. THE ARMATURE PORTION FACING THE CORE AND THE POLE RING IS IN THE SHAPE OF A FLAT DISK, THE REST OF THE ARMATURE BEING MADE OF A LIGHT-WEIGHT METAL.

NOV. 14, 1972 M R 3,702,683

FUEL INJECTION VALVE Filed Nov. 22, 1971 5 45 jrropA/ry United States Patent Office 3,702,683 Patented Nov. 14, 1972 3,702,683 FUEL INJECTION VALVE Hans Sturmer, Stuttgart, Germany, assignor to Robert Bosch GmbH, Stuttgart, Germany Filed Nov. 22, 1971, Ser. No. 200,967 Claims priority, application Germany, Dec. 18, 1970, P 20 62 420.8 Int. Cl. B05b 1/30 U.S. Cl. 239-585 Claims ABSTRACT OF THE DISCLOSURE A fuel injection valve for internal combustion engines has a housing having a fuel inlet and a fuel outlet. The housing has a valve seat having an axis at the fuel outlet. A valve member is arranged within the housing and axially aligned with the valve seat and movable along the axis of the valve seat between a first position spaced from the valve seat and a second position engaging the valve seat. An electromagnet is provided within the housing which includes an armature connected to the valve member and together forming a unit for moving the valve member when said electromagnet is energized from the second position to the first position. A spring, anchored at one end to the housing, cooperates with the unit and connected thereto to yieldably maintain the valve member in the second position. Two membranes are provided within the housing which are spaced from one another in axial direction of the valve means. The membranes define substantially parallel planes, each membrane being connected to the unit and to the housing for maintaining a valve member in axial alignment with the valve seat. The electromagnet has a central core coaxial with the valve seat axis and a coaxial annular pole ring. The armature has a portion which is made from soft iron and which faces the core and the pole ring. The armature portion facing the core and the pole ring is in the shape of a flat disk, the rest of the armature being made of a light-weight metal.

BACKGROUND OF THE INVENTION The present invention relates to fuel injection valves, and particularly to fuel injection valves for internal combustion engines using suction fuel injection.

Injection valves which utilize electromagnets for controlling their operation are already known. In the known injection valve, the needle valve is connected to the armature of an electromagnet. The armature is mounted for linear movement within the electromagnet housing in response to energization of the electromagnet winding. By energizing the winding coil at proper times during the operation cycle of the combustion engine, the armature. as well as the valve, move to open a fuel outlet to thereby inject fuel into the combustion engine.

However, fuel injection valves may be operated at very fast speeds and the needle valves must be capable of responding to very short electrical impulses. In the prior art injection valves, the mass of the armatures have generally been large. Accordingly, the inductance of the electromagnetic winding has been large in order to increase the forces applied to the armature to thereby seek to decrease the actuation time. Moreover, both for the reasons that the armature mass is large and also because the winding inductance is high, the prior art injection valves have always been limited in their short time response. Because the fuel release time of the outlet opening is a function of the mass of the armature, the inductance of the electromagnet as well as the width of the activating pulse, the actual period of time during which the fuel outlet is open does not always correspond to the width of the pulse which was applied to the winding. This situation was especially true when the width of the pulses applied to the electromagnet winding has been small and in the order of 1 millisecond. The inability of the prior art injection valves to accurately control the quantity of fuel delivered to a combustion engine, has caused these engines to operate less efficiently. and, in many instances, emit a greater proportion of undesirable exhaust gases.

Other known injection valves for internal combustion engines used various guide means for guiding the needle valve to thereby position it concentrically in the axis of the fuel outlet valve seat. Such arrangements for guiding the needle valve have generally resulted in frictional forces being formed between the needle valve and the guide means. These frictional forces, after continuous use, tended to wear out the guide means, whereby the needle valve was thereafter no longer maintained in perfect coaxiality with the valve seat. Such loss of coaxiality may result in improper seating of the valve to thereby permit the flow of fuel into the combustion engine, even when this is not desired. Such leakage into the combustion engine causes inefficient operation and usually results in undesired exhaust gases being formed from incomplete combustion of the fuel.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection valve, for internal combustion engines which does not possess the disadvantages found in the prior art.

Another object of the present invention is to provide a fuel injection valve for internal combustion engines which is simple in construction and inexpensive to manufacture and which can accurately provide desired quantities of fuel to the combustion engine.

Still another object of the present invention is to provide a fuel injection valve for internal combustion engines which can operate at very fast speeds and which can open and close in time intervals of about 1 millisecond.

A further object of the present invention is to provide a fuel injection valve for internal combustion engines which does not have any elements which encounter friction during operation of the valve which may cause wear on these elements.

According to the present invention a fuel injection valve for internal combustion engines comprises a housing having a fuel inlet and a fuel outlet and forming a valve seat having an axis. A. valve member is arranged within said housing and axially aligned with said valve seat and movable between a first position spaced from said valve seat and a second position engaging said valve seat. An electromagnet means within said housing includes an armature fixed to said valve member and forming a unit with the same for moving the valve member when said electromagnet is energized from said second position to said first position. Biasing means are provided which cooperate with said unit and said biasing means is connected to the unit to yieldably maintain said valve member in said second position. At least one membrane extends transversely through said housing and is connected to said unit for maintaining said valve member in axial alignment with said valve seat.

According to the presently preferred embodiment, two membranes are provided which are spaced from one another in the axial direction of said valve seat. The membranes have outer peripheries which are fixed to said housing. Said membranes define substantially parallel planes, each membrane being connected to said unit and to said housing for maintaining the valve member in axial alignment with said valve seat. Said electromagnet means has a central core coaxial with said valve seat axis and a coaxial annular pole ring. The armature portion has a thickness in the axial direction which is substantially less than its outer diameter and the rest of the armature is made of a light weight metal.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING The single figure is a side elevational view, in crosssection of a fuel injection valve for internal combustion engines according to the present invention, showing the valve member closing the outlet opening of the injection valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, a fuel injection valve is illustrated which has a housing 1. The housing 1 is shown to be generally cylindrical or tubular. The housing 1 has a narrow portion or neck 2. The housing 1, as well as the neck 2, can be made of steel or other suitable magnetic conducting materials. Held within the neck 2 is a central core 3 which is tubular, as shown, and is likewise made from a magnetic conducting material, such as iron. The neck 2 and the central core 3 are fitted, such as pressfitted, so as to leave no airgap between the two.

The central core 3, at one end, contains a fine-meshed sieve 4 to filter the fuel coming from a fuel tank prior to being injected into the combustion engine.

In the presently preferred embodiment, the housing 1 is substantially cylindrical and has an axis which coincides with the axis of the central core. An armature 5 is likewise coaxially mounted with the housing 1.

The central core 3 conducts the fuel through the sieve down to the region of the armature 5. A radial groove 6, provided in the central core 3, is used to pass the fuel into the lower portion of the injection valve.

A winding spool 7 is arranged between the hole of the housing 1 and the central core 3, the winding spool carrying an exicting winding 8 of the electromagnet. The exciting winding 8 is adapted to receive electrical voltages which cause magnetic fields to be generated in the magnetic circuit formed by the electromagnet. Thus, the primary magnetic circuit consists of the housing 1, and the central core 3. The armature 5, which also forms part of the electromagnetic circuit, moves along the axis of the housing to thereby change the reluctance of the magnetic circuit in response to energization of the exciting winding 8.

Connected to the armature 5, is a valve member or needle valve 10. As shown, the needle valve 10 has an injection plug 11 which is slightly tapered outward away from the housing 1. The injection plug 11 meets a scaling edge 12 which is tapered in the other direction. The sealing edge 12 is coaxial with a valve seat 13. The valve seat 13 can comprise a conical or spherical seat surface. It is also important in this respect, that the sealing edge 12 can matingly fit and abut against the valve seat 13 to thereby seal the outlet opening of the injection valve. The particular needle valve-valve seat arrangment is not critical for the purposes of the present invention, the type shown only being for illustrative purposes, and any needle valvevalve seat arrangement known in the art can be used. The valve seat 13 is formed along the axis of the housing 1 at the bottom of said housing, which can be designated as the injection head 16.

Two membranes 20 and 21 are provided which are spaced from one another in the axial direction of the housing 1, said membrane defining substantially parallel planes. Each membrane is connected to the armature 5 for maintaining the needle valve 10 in axial alignment with the valve seat 13.

The membranes 20 and 21 are provided with holes 20' and 21' respectively for passing the fuel received from the radial groove 6 to the injection head 16. Thus, the fuel is transported front the fuel tank through the fine meshed sieve 4 down through the central core 3, to the radial groove 6, through the holes 20' and 21, into the injection head 16, and finally through the fuel outlet controlled by the valve seat 13 and the needle valve 10.

Biasing means or a closing spring 15 is provided within the confines of the central core 3 for urging the armature 5 in a direction to increase the reluctance of the magnetic circuit of the electromagnet. At the same time, since the needle valve 10 is connected to the armature 5, the closing spring 15 urges the needle valve 10 in a downward position to close the fuel outlet. The closing spring 15 is anchored at one side by the sleeve 15' which is pressfitted inside the central core 3 to prevent the movement of the sleeve 15' within the central core. The armature 5, in the deenergized condition of the winding 8, is centrally positioned by the membranes and 21 while the closing spring 15 urges the sealing edge 12 to bear against the valve seat 13 to thereby cut off the flow of fuel. In the closed position of the valve, the armature 5 is spaced from the core 3 by a small air gap 26 which represents the total movement which the needle valve 10 can make.

Annular spacers 27, 35 and 36 are used to space the membranes 20 and 21 as well as fix the inner and outer peripheries of the membranes to prevent their movement relative to the housing 1.

Fitted within the armature S is a threaded socket 24 which is rigidly connected to the armature 5. The upper portion of the needle valve 10 is provided with a threaded portion 25 which together with the threaded socket form connecting means for connecting the needle valve 10 and ths armature 5. The use of threaded portions permits the adjustment, in the axial direction, of the armature 5 in relation to the needle valve 10 to insure that the sealing edge 12 in fact abuts against the valve seat 13 in response to the action of the closing spring 15 when the exciting winding 8 is not energized. Also the needle valve 10 must not be extended too far out of the threaded socket 24 since this would effectively decrease the air gap 26 and reduce the amount of movement which the needle valve II) can make. After the needle valve 10 has been properly adjusted to provide both proper sealing as well as proper air gap space, the axial position of the needle valve 10 in relation to the threaded socket 24 can be assured by applymg an adhesive 37 which, after hardening, effectively locks the needle valve in place to prevent rotation of the needle valve which may result in its axial displacement.

The magnetic field which is created by the exciting winding 8 passes through a magnetic path consisting of the housing 1, the central core 3, the air gap 26, the armatare 5, the variable air gap between the armature 5 and the annular pole ring 32 and finally back to the housing 1. As well known, the energization of the exciting winding 8 will cause a magnetic flux to fiow through the aforementioned magnetic circuit, the tcndency being to decrease the magnetic reluctance of the circuit. Accordingly, die armature 5 will be drawn up towards the central core 3 to decrease the air gap 26 as well as the gap between the armature 5 and the pole ring 32. The upward movement of the armature 5 will compress the closing spring 15, which spring is selected to apply appropriate forces on the armature 5 to permit both the movement of the armature 5 a distance approximating the dimension of the air gap 26 as well as returning the armature 5 and the needle valve 10 to the position shown in the figure as soon as the energization is removed from the exciting winding 8.

Since only the portion of the armature 5 which faces the central core 3 is conducting the magnetic flux in the magnetic circuit of the electromagnet, it is, according to the presently preferred embodiment of the invention, only this portion which must be made of a soft iron material which provides a good conduction path for the magnetic flux. The materials used for the magnetic circuit are well known and the particular materials used for the central core, housing of the armature does not form part of the present invention. However, in order to reduce the weight of the moving parts, in particular the part of the armature which does not conduct substantial magnetic flux, these parts can be made from a light weight metal, such as aluminum. The parts which are preferably made from a light weight metal include the bottom portion of the armature 5, the threaded socket 24, as well as the needle valve 10. Use of light weight metals for these parts reduces the mass of the moving unit to thereby enable more dynamic responses upon the application of pulses to the exciting winding 8. Also, the portion of the armature 5 which conducts the major part of the magnetic flux, that is portion 28, is preferably made in the shape of a thin flat disk. Such a configuration reduces the mass of the magnetic conducting portion of the armature 5 to the minimum required to further enable the movable unit to quickly respond.

Although the presently preferred embodiment has been illustrated as having two membranes 20 and 2 1, this is only illustrative and any number of membranes can be used. One membrane may be suitable for certain applications. The membranes 20 and 21 are shown to have holes 20' and 21', respectively, which permit the flow of fuel from the central core 3 to the injection head 16.

In the normally deenergized condition of the exciting winding 8, the armature plate 28 is spaced from the central core 3, as shown in the figure. During this time, fuel, passing through the central core 3, can be furnished to the injection head 16 through the radial groove 6 and the central bore 30 in order to replenish amounts which have been dispensed through the fuel outlet. The actual dimension of the air gap 26 in the deenergized state is not critical for the purposes of the present invention, although 006 millimeter has been found to be suitable for fuel injection purposes. This is especially true in combustion engines which utilize suction to draw the fuel out of the injection valve.

With the arrangement as described the unit consisting of the armature 5 and the needle valve 10 are maintained in a perfectly coaxial relationship with the valve seat 13 to insure proper opening and closing of the fuel outlet. This is done without frictional engagement for the generation of heat. The use of the membranes and 21, prevents the needle valve 10 from tipping or tilting at any time during operation to thereby minimize wear on the valve seat 13.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of injection valves differing from the types described above.

While the invention has been illustrated and described as embodied in a fuel injection valve for internal combustion engines, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can apply current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the generic or specified aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. A fuel injection valve for internal combustion engines, comprising a housing having a fuel inlet and a fuel outlet and forming in said housing a valve seat having an axis; a valve member arranged within said housing and axially aligned with said valve seat and movable between a first position spaced from said valve seat and a second position engaging said valve seat; electromagnet means within said housing and including an armature fixed to said valve member and forming a unit with the same for moving the valve member when said electromagnet is energized from said second position to said first position; biasing means cooperating with said unit and connected thereto yieldably maintain said valve member in said second position; and at least one membrane extending transversely through said housing and connected to said unit for maintaining the valve member in axial alignment with said valve seat.

2. A fuel injection valve as defined in claim 1, wherein said housing is substantially cylindrical and has an axis which coincides with said valve seat axis, said armature being positioned for linear movement along said axis.

3. A fuel injection valve as defined in claim 1, wherein said membrane has an outer periphery which is fixed to said housing.

4. A fuel injection valve as defined in claim 1, wherein two membranes are provided which are spaced from one another in the axial direction of said valve seat, said membranes defining substantially parallel planes, each membrane being connected to said unit and to said housing for maintaining the valve member in axial alignment with said valve seat.

5. A fuel injection valve as defined in claim 1, further including connecting means for connecting said valve member to said armature for adjustment relative to each other in the direction of said axis.

6. A fuel injection valve as defined in claim 5, wherein said connecting means comprises thrcadingly engaged portions on said armature and said valve member.

7. A fuel injection valve as defined in claim 6, wherein said armature and said valve member are maintained in fixed relation one with respect to the other in the axial direction of said valve seat by adhesive applied to both said armature and said valve member of adjoining surface areas.

8. A fuel injection valve as defined in claim 1, wherein said electromagnet means has a central core coaxial with said valve seat axis and a coaxial annular pole ring, said armature having a portion which faces said core and pole ring and which is made from soft iron.

9. A fuel injection valve as defined in claim 8, wherein said armature portion has an outer diameter, the thickness of said portion in the axial direction being substantially less than said outer diameter.

10. A fuel injection valve as defined in claim 9, wherein said armature portion is in the shape of a Hat disc, the rest of the armature being made from alight weight metal.

References Cited UNITED STATES PATENTS 2,130,666 9/1938 Coffey 239-585 X 3,004,720 10/1961 Knapp et al. 239585 3,241,768 3/1966 Croft 239585 X M. HENSON WOOD, 111., Primary Examiner E. D. GRANT, Assistant Examiner 

